Note: Yes, my table is wobbly. It was very late, I was very tired, and that is that. I have now saved you the trouble of pointing it out. 😘 It's testing day for the library science interns. Let's check them in one by one and get ready for the test, maybe getting a little work done in between.
To listen while using other apps, switch the player to Picture-in-Picture (PiP) during playback — it keeps playing in a small floating window (the screen stays on).
To listen with the screen fully off, in-browser playback stops by YouTube's design. Open the video in the YouTube app to keep listening where background playback is supported (e.g. with YouTube Premium).
Open in YouTube app